If you're talking about a desktop, wouldn't it be easiest just to rewire the SATA cables so the permanent disk is the first primary drive, meaning it would be /dev/sda ?? Then you'll just need to make a new grub.cfg so it knows where it is, and removing the second drive will have no effect. If you use the second drive to boot windows, you can still select to boot from that in BIOS with no impact.

It's a desktop. When I was installing gentoo I had these 2 hdds and a usb flash drive were attached to the box. I booted from systemrescuecd on the flash drive. It named the removable hdd as sda, the one that's gentoo is installed as sdb and it's ownself as sdc. I suggest even if I rewire grub2 will seek somethimg to mount to.

You're right the error should be somethig other than (0 0) but it is (0 0)

I think the problem is because grub2 is unnecesarrily automated. If I can't edit grub2 I will try grub.